The Dual-Specificity Phosphatase CDC14B Bundles and Stabilizes Microtubules

Abstract

The Cdc14 dual-specificity phosphatases regulate key events in the eukaryotic cell cycle. However, little is known about the function of mammalian CDC14B family members. Here, we demonstrate that subcellular localization of CDC14B protein is cell cycle regulated. CDC14B can bind, bundle, and stabilize microtubules in vitro independently of its catalytic activity. Basic amino acid residues within the nucleolar targeting domain are important for both retaining CDC14B in the nucleolus and preventing microtubule bundling. Overexpression of CDC14B resulted in the formation of cytoplasmic CDC14B and microtubule bundles in interphase cells. These microtubule bundles were resistant to microtubule depolymerization reagents and enriched in acetylated α-tubulin. Expression of cytoplasmic forms of CDC14B impaired microtubule nucleation from the microtubule organization center. CDC14B is thus a novel microtubule-bundling and -stabilizing protein, whose regulated subcellular localization may help modulate spindle and microtubule dynamics in mitosis.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://mcb.asm.org/.

ACKNOWLEDGMENTS

We thank Lea Harrington and Angelika Amon for critical reading of the manuscript and Ashley Davis for technical support regarding the in vitro MT-bundling assay. We also thank Angelika Amon for the cdc14-3 strain and Kathy Gould for the pGAL-clp1 plasmid.

Y.W. acknowledges the support of the Laboratory Directed Research and Development Program (LDRD), Oak Ridge National Laboratory, and the Office of Biological and Environmental Research, U.S. Department of Energy, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. H.P.C. is a postdoctoral fellow supported by LDRD. M.T. is supported by grants from the Canadian Institutes of Health Research and holds a Canada Research Chair in Functional Genomics and Bioinformatics.